export const debounce = (fn, delay) => {
  let timer = null

  // 返回的函数是用户每次实际调用的函数
  return function (...args) {
    if (timer) clearTimeout(timer)
    timer = setTimeout(() => {
      fn && fn.apply(this, args)
    }, delay)
  }
}
// 时间戳方案--节流
export function throttle(fn, wait) {
  var pre = Date.now()
  return function () {
    var context = this
    var args = arguments
    var now = Date.now()
    if (now - pre >= wait) {
      fn.apply(context, args)
      pre = Date.now()
    }
  }
}

/** 数组去重 */
export function distinct(arr) {
  const newArr = []
  let isExist = false
  for (let i = 0, length = arr.length; i < length; i++) {
    for (let j = i + 1; j < length; j++) {
      if (arr[i].name == arr[j].name) {
        isExist = true
        break
      }
    }
    if (!isExist) {
      newArr.push(arr[i])
    }
    isExist = false
  }
  return newArr
}

/** 时间格式化函数
 * @param date          @new Date()一个Date对象
 * @param fmt           时间格式化时间，'yy-MM-dd'
 */
export function formatDate(date, fmt) {
  if (/(y+)/.test(fmt)) {
    fmt = fmt.replace(RegExp.$1, (date.getFullYear() + '').substr(4 - RegExp.$1.length))
  }
  const o = {
    'M+': date.getMonth() + 1,
    'd+': date.getDate(),
    'h+': date.getHours(),
    'm+': date.getMinutes(),
    's+': date.getSeconds()
  }
  for (const k in o) {
    if (new RegExp(`(${k})`).test(fmt)) {
      const str = o[k] + ''
      fmt = fmt.replace(RegExp.$1, RegExp.$1.length === 1 ? str : padLeftZero(str))
    }
  }
  return fmt
}

function padLeftZero(str) {
  return ('00' + str).substr(str.length)
}
